1. Field of the Invention
The present invention relates to a method of using a large screen low-density dot-matrix display device to display high-density bit-mapped dot-matrix image data. Specifically, the present invention relates to a method of obtaining as fine an image as possible through the aforesaid large screen dot-matrix display.
2. Description of the Related Art
Large-scale dot-matrix displays of the type consisting of an array of vertically and horizontally oriented rows of light emitting diodes are frequently used on buildings, in sports stadiums, and at other locations as a means of imparting information visually. These types of displays use large display surfaces which generally offer a similar image resolution to that of conventional television.
A typical television receiver offers a level of image resolution equivalent to 480 vertical and 720 horizontal display lines. Bit mapped image data applied to this resolution standard is processed as 480 vertical dots by 720 horizontal dots. If this data display standard were to be applied to a large screen dot-matrix display having, for example, a 96 vertical by 144 horizontal dot pattern, the result would be a display that offers only one fifth of the resolution that the bit-mapped image data is capable of.
The simplest way to execute control of this type of display is to thin out the horizontal and vertical dot density to one fifth normal density whereby the 480 by 720 bit-mapped image data is re-formatted into the 96 by 144 pattern, and to drive each dot in the 96 by 144 dot pattern with one bit of data. Through this method, only one dot of image data is used to drive one dot of display within an area in which 25 dots (5xc3x975) of image data are available.
A significant amount of data is lost and image resolution lowered as a result of this image thinning display control method. Furthermore, when only this thinning process is applied, an aliasing effect is generated which significantly lowers image quality. It is known in the art that image format conversion, a process in which image data within a very small image area is averaged, can be applied to reduce the adverse affects of aliasing. Aliasing can be reduced, for example, through the averaging conversion offered by a low-pass filter in which one dot of image data is averaged from twenty five (25) dots (5xc3x975), or from nine (9) dots (3xc3x973) within the 5xc3x975 dot area (in this case, sixteen (16) dots of data (25-9) are ignored). After this format conversion is executed, that one dot of averaged image data is used to drive one display dot on screen. It is also known in the art that a weighted averaging format conversion operation can be applied in which the central portion of a small group of dots is specifically stressed, or xe2x80x9cweightedxe2x80x9d in the data conversion process. Bilinear, cubic spline, and Gaussian filters are some examples of weighted averaging format conversion.
Low-density bit-mapped image data can be derived from high-density image data through an averaging format conversion process and displayed on a large-scale low-density dot-matrix display device. Once the required control parameters are set, this method results in improved image quality when compared to simple image thinning.
With respect to a structure of display devices, it is advantageous to employ a low-density dot-matrix device for the above high-density image display since recent examples of large-scale display systems generally include a relatively thick and solid panel structure, in which a number of light emitting elements such as a high-intensity LED combination lump. Because of electronic devices for driving the elements installed in the panel structure, the panel structure cannot be transparent. However, in today""s planning and designing of buildings with various types of facades such as a curtain wall, there arise needs for a large-scale display device capable of maintaining visibility through the display device as well as the facade. Obviously, the above conventional display device with a solid panel structure cannot be employed for this use.
It is an object of the present invention to provide a method of using high-density bit-mapped image data to drive a low-density dot-matrix type display device by means of a new display control standard wherein higher visible image resolution is achieved compared to conventional methods.
It is another object of the present invention to provide a display device having a transparent structure capable of maintaining visibility across its structure.
According to one aspect of the present invention, a method of using high-density bit-mapped image data to drive a low-density dot-matrix display device, comprises the steps of allocating each of multiple dot groups oriented in mutual proximity in bit-mapped image data for one display dot on the display device, applying a predetermined image data selection sequence standard to alternately select one image dot of data from within each of the multiple dot groups by means of a repetitive high-speed data selection operation, and supplying each dot portion of the alternately selected data to the display device as one dot of display drive data. The predetermined image data selection sequence standard may include a predetermined image data calculation standard.
According to another aspect of the present invention, a system for displaying high-density dot-matrix bit-mapped image data on a low-density dot-matrix display, employs a method comprising the aforesaid steps.
According to yet another aspect of the present invention, a dot-matrix display device comprises a plurality of cross members intersecting with each other at such intervals as substantially larger than a width of each of the cross members, a plurality of light emitting elements disposed at the intersecting points of the cross members respectively, each of the light emitting elements being shaped so as not to deteriorate transparency of a structure configured by the intersecting cross members, each of the light emitting element being so disposed that an optical axis thereof is oriented substantially perpendicular to a surface of the structure formed by the intersecting cross members, and means for controlling drive of the light emitting elements respectively, the controlling means being distributed in the cross members. The display device may further comprise a plurality of display modules, each of which having substantially the same configuration as the aforesaid display device.
Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein only the preferred embodiment of the invention is shown and described, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.